This evening while driving down the road out of the blue the radio volume went from where it was at (setting 10 or so) to zero.  My immediate reaction was to turn it back up with my steering wheel controls, and it went back up, but the minute I let off it, it went right back to zero.  I first thought it was the steering wheel controls, but.... I then tried adjusting the volume back up on the headunit itself, and nothing.  So..... I finally got the volume to stay up/adjust with the steering wheel controls where I wanted it.  I then tried turning the volume down on the head unit.  Nothing...... So... I started testing out other buttons of the headunit. 

Neither the volume up/down work, or the mute button.  All other buttons of the headunit work properly!  Can anyone please shed some light on this, or point me in the right direction of what I need to do?

Thanks!

On a updated side note, I got in the truck this morning to go to work and when the headunit came on it was in the mute function.  I tried unmuting it with mute button on the headunit and no luck.  So... I hit the volume up button on the steering wheel controls and it took it out of mute.  Drove for about 4 seconds and it put itself back on mute, then off, then volumed up, then mute.  To stop any of this I had to hit a button on the steering wheel controls because still on the headunit the volume/mute keys are dead to the world.

Per another site and from Pioneer's Tech Support I was told to disconnect my steering wheel control interface and see if the problem goes away.  Well, on my lunch hour I did so, and that did not fix the problem.  The headunit buttons still didnt work when that was disconnected   Looks like a 1yr old headunit is now useless to me.  I'd hate to think what its going to cost to repair it.